In recent years, cellular telephones, portable computers, and similar devices have included the capability of imaging picture information for viewing and recording with the use of an included imaging device. Furthermore, the imaging optical systems used in such imaging devices must be lightweight and compact for such applications in devices such as cellular telephones and portable computers. Additionally, technology has been developed in order to make such devices thinner in thickness by bending the optical axis of the optical systems by arranging prisms on the optical axis when the objective plane is in the thickness direction of the imaging device.
Moreover, there has also been a demand for higher level functions in the imaging optical systems in such imaging devices, and imaging optical systems having a zoom function have been proposed, for example, in Japanese Laid-Open Patent Application 2004-212737 and Japanese Laid-Open Patent Application 2004-151552.
When the imaging optical system is miniaturized, blurring occurs in the image being recorded when a slow shutter speed is used for recording because vibration caused by movement of a hand or hands holding the imaging device is transmitted to the imaging optical system. For this reason, high quality picture images frequently cannot be obtained due to image blurring.
A particular problem with imaging devices that include a zooming function is that blurring of images due to hand movement is especially significant at the telephoto end of the zoom range.
The technology described in Japanese Laid-Open Patent Application 2004-212737 and Japanese Laid-Open Patent Application 2004-151552 makes use of a first lens group having negative refractive power as a whole and including a prism, causing the diameter of diaphragms or stops used to increase in size and making the device thicker in the thickness direction.
The technology described in Japanese Laid-Open Patent Application 2004-212737 further has a limit to the miniaturization of the prism because the prism is provided at the object-most side of the first lens group.